There are two Two methods that can be used to add a Trunk Group. The most common method is to click the + Add Trunk Group button from on the Relationship’s Trunk Groups page.
...
The second method is to use the Quick Add feature. This feature can be accessed from on Relationship page (see image above) or from the Relationships table. In the Relationships table, find the relationship to modify in the main window and move your mouse cursor to the right of the STATUS field for that relationship. Left click on the three vertical dots that appear elipssis and the select Quick Add. Then select Click Trunk Group.
...
Add a Trunk Group name in the Name field.
Add an Origination or Termination direction in the Direction field.
Add a Customer or Vendor relationship in the Relationship field.
Click the Create Button.
Once the Trunk Group is created, the Direction and Relationship cannot be changed. However, the Trunk Group can be renamed.
...
See the appropriate Trunk Group type for details on how to properly add a given Trunk Group type.